Conventionally, techniques of using a biological sample to analyze components making up the biological sample have been provided. In the techniques, a dedicated container is prepared so that a biological sample taken from a patient is processed in the container. For example, where the sample is blood, the blood sampled is injected into a test tube with a separating agent pre-placed therein. Then, the test tube is subjected to centrifugation, so that the blood is separated into clot and serum in order to extract serum which is a component necessary for analysis.
Recently, inspection items that may be measured using serum has been diversified. As a result, the number of automatic analysis devices is increased, and thus an increase in number of samples is remarkable. Under the circumstances, there is an increasing need for systems for automatically processing (preprocessing) a biological sample before the biological sample is loaded into the automatic analysis device and/or for automatically transporting the sample to the automatic analysis device.
Examples of the pre-processes include a process to detect the amount of serum. If the amount of serum is uncertain, a probe may stick in the separating agent in the aliquot process to lead to a clogging error. If the amount of serum can be detected in the stage of preprocessing, then the probe height can be controlled to avoid the clogging error. Further, if the amount of serum is less than the amount required for analysis, analysis items are provided with priorities to determine an aliquot amount. Thus, if the amount of serum is able to be detected in the state of preprocessing, the enhanced efficiency of the measurement test using serum may be expected.
As a technique to detect the amount of serum or a technique to measure the position of liquid surface of a sample such as serum or the like, Patent Literature 1 discloses the interface-position determining method that uses a first light beam which passes through serum but is blocked by clot and a second light beam which is blocked by both serum and clot to detect the light resulting from the first and second beams being transmitted through the container. Further, Patent Literature 2 discloses the configuration that uses a line sensor to detect the transmitted light from the infrared surface light source to identify the serum interface position. Also, Patent Literature 3 discloses the configuration that uses derivative value data to detect the liquid surface position.